Field of the Invention
The present invention relates to an image processing apparatus for performing image processing on a radiation image, and a recording medium.
Description of the Related Art
A radiation image obtained by irradiating an object with a radiation includes not only a primary radiation component traveling straight from a radiation source but also a scattered radiation component which is a radiation scattered in the object. The scattered radiation component may possibly degrade the contrast of the radiation image. As a technique for reducing a scattered radiation component in an X-ray image, US2010/0208870 discusses a technique for obtaining a primary X-ray image in such a manner that the scattered radiation component is modeled using a formula obtained by performing a convolution of a formula expressed by a primary X-ray with two Gaussian functions.
FIG. 9A is a diagram illustrating an example in which measurement is performed by using a thoracic phantom and a scattered radiation component included in a radiation image is acquired on an experimental basis. Referring to FIG. 9A, the scattered radiation component includes what is called a skin line 903 at the boundary between a region (through-exposure region) 901 irradiated with an X-ray that passed through the periphery of an object without penetrating the object and an object region 902. This phenomenon occurs because, depending on the object's thickness, a radiation that entered the object scatters in a different mode and is not scattered in the through-exposure region 901 whereby an intensity distribution of the scattered X-ray becomes discontinuous.